Another man - Rudy Guede from Ivory Coast - was convicted in a separate trial and sentenced to 16 years for the killing.

The case has drawn intense media interest in Italy, the UK and the US, and put the Italian police and justice system under great scrutiny.

"I was in the courtroom [in Italy] when they were calling me 'devil'," Ms Knox says in the ABC interview.

"It's one thing to be called certain things in the media and then it's another thing to be sitting in a courtroom, fighting for your life, while people are calling you a devil.

"For all intents and purposes, I was a murderer - whether I was or not. And I had to live with the idea that that would be my life."

She adds that what happened to her "was surreal but it could've happened to anyone".

The interview is timed to coincide with the release of Ms Knox's autobiography (Waiting to Be Heard), for which she was reportedly paid more than $4m (£2.5m), the BBC's David Willis in Washington reports.

In the book, she maintains that on the night of Meredith Kercher's death she was at Raffaele Sollecito's flat smoking marijuana and watching a movie.

The Italian courts cannot compel her to return for the retrial but they could request her extradition - at which point it would be up to the US authorities to determine her fate, our correspondent says.